无法使用smtp relay发送Mail，Ruby mail gem

Question

我正在尝试使用'mail'gem发送电子邮件（使用OCRA打包），但我收到一条错误消息：

=== Loading script to check dependencies
C:/Ruby23/lib/ruby/gems/2.3.0/gems/mail-2.6.6/lib/mail/check_delivery_params.rb:
13:in `check_from': SMTP From address may not be blank: nil (ArgumentError)
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/mail-2.6.6/lib/mail/check_delive
ry_params.rb:6:in `check'
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/mail-2.6.6/lib/mail/network/deli
very_methods/smtp.rb:97:in `deliver!'
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/mail-2.6.6/lib/mail/message.rb:2
149:in `do_delivery'
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/mail-2.6.6/lib/mail/message.rb:2
39:in `deliver'
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/mail-2.6.6/lib/mail/mail.rb:141:
in `deliver'
        from c:/BacklogAlert.rb:140:in `send_email'
        from c:/BacklogAlert.rb:163:in `<top (required)>'
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/ocra-1.3.10/bin/ocra:1211:in `lo
ad'
        from C:/Ruby23/lib/ruby/gems/2.3.0/gems/ocra-1.3.10/bin/ocra:1211:in `<t
op (required)>'
        from C:/Ruby23/bin/ocra:22:in `load'
        from C:/Ruby23/bin/ocra:22:in `<main>'

问题是我们正在使用内部smtp邮件中继，它只允许设备发送给内部收件人，因此不需要“发件人”地址。

这是我的代码：

  Mail.defaults do
      delivery_method :smtp, mail_options
    end

    Mail.deliver do
           to email_recipient
         from email_sender
      subject 'Test email ' + today_date
         body 'Attached is a file'
         add_file test_file
       end

如何在不指定“发件人”地址的情况下收到要发送的电子邮件？